High-frequency power semiconductor module with a hollow housing and method for the production thereof

ABSTRACT

The invention relates to a radiofrequency power semiconductor module having a cavity housing constructed from three modules, a 1st module, which has an upwardly and downwardly open housing frame with horizontally arranged flat conductors, a 2nd module, which has the chip island as a heat sink with at least one radiofrequency semiconductor components, the 2nd module forming the bottom of the cavity housing, and a 3rd module, which has the housing cover.

FIELD OF THE INVENTION

The invention relates to a radiofrequency power semiconductor modulehaving a cavity housing and having at least one radiofrequencysemiconductor component and having a chip island, on which theradiofrequency semiconductor component(s) is/are arranged, and to amethod for producing it.

BACKGROUND

On account of the high evolution of heat and the radiofrequencyproperties, radiofrequency power semiconductor modules are accommodatedin cavity housings made of ceramic. Moreover, it is possible toconstruct high-power modules which are packaged completely in plasticscomposition and whose radiofrequency semiconductor components arearranged on a chip island, at least one surface of which forms an outerwall of the housing that can be cooled by the surroundings. However, theuse of such high-power modules for radiofrequency applications islimited on account of the dielectric properties of the plastic housingcomposition into which the radiofrequency semiconductor components areembedded.

The flat conductor frames required for devices of this type areconstructed in extremely complex fashion since, on the one hand, theyhave to afford a first plane for free-standing flat conductors and, onthe other hand, they have to afford a second plane with a solid metallicchip island for dissipating the heat. The technical outlay and outlay oncosts for flat conductor frames of this type is of a similar magnitudeto that for ceramic cavity housings. However, the heat dissipation ofceramic cavity housings is not particularly effective. Moreover, bothhousing forms have the disadvantage that the seating or the fixing ofthe radiofrequency semiconductor component can only be successfullytested when the radiofrequency semiconductor components are accommodatedand wired in the relatively expensive housing forms, so that functionaland quality tests can only be used relatively late for the known housingforms.

Therefore, it is an object of the present invention to specify aradiofrequency power semiconductor module which overcomes thedisadvantages in the prior art and can be produced inexpensively with areduced failure rate.

This object is achieved by means of the subject matter of theindependent claims. Advantageous developments of the invention emergefrom the subclaims.

The invention specifies a radiofrequency power semiconductor modulehaving a cavity housing and at least one radiofrequency semiconductorcomponent arranged in the cavity housing. Moreover, the cavity housinghas a chip island, on which the radiofrequency semiconductor componentsare arranged. Furthermore flat conductors are anchored in a housingframe closed off by a housing cover. This radiofrequency powersemiconductor module has three prefabricated modules, a 1st modulehaving flat conductors arranged horizontally in the upwardly anddownwardly open housing frame. A 2nd module has the chip island as aheat sink with at least one radiofrequency semiconductor component andforms the bottom of the cavity housing. The 3rd module closes up thecavity housing toward the top and has the housing cover.

A radiofrequency power semiconductor module of this type which iscomposed of three modules has the advantage that each module caninherently be tested in respect of its quality and functionality beforethe three modules are assembled to form an electronic device. What isparticularly advantageous in this case is that the radiofrequencysemiconductor component can already be positioned on a heat sink thatreplaces the previous chip island of a flat conductor frame.Consequently, the chip island can be produced completely independentlyof a flat conductor frame with simple means and forms the bottom of thecavity housing, which constitutes a lowering of the production costssince there is no need to provide complex flat conductor frames having,in two separate planes, on the one hand flat conductors and on the otherhand a chip island that can be cooled externally. Such a complexconstruction of a three-dimensional flat conductor frame for realizing aradiofrequency power semiconductor module with a cooled chip island canconsequently be avoided.

Moreover, it is possible to qualitatively and functionally check thesecure anchoring of the radiofrequency semiconductor components on thechip island, furthermore the electrical contact between theradiofrequency semiconductor components and the chip island and thepositioning of the radiofrequency semiconductor components on the chipisland before the 2nd module is assembled with the 1st module. Thisadvantage becomes particularly apparent when a plurality ofradiofrequency semiconductor components are to be accommodated on theheat-dissipating chip island.

A further advantage of the radiofrequency power semiconductor moduleaccording to the invention is that the housing frame with flatconductors anchored therein can be produced as an independent module inmass production and it is possible to check the dimensional accuracy andprecision of the housing frame in conjunction with the flat conductorsanchored therein prior to assembly with the 2nd module. Consequently,the probability of only functional 1st modules being mechanicallyconnected to functional 2nd modules to form an upwardly open cavityhousing is improved and the failure rate after the connection of theflat conductors in the interior of the cavity housing to the electrodesof the radiofrequency semiconductor components is reduced.

In this respect, it should be noted that radiofrequency powersemiconductor modules are to be realized by connecting hundreds ofbonding wires in parallel on a flat conductor end to a correspondingelectrode of a radiofrequency power semiconductor, so that it isadvantageous if it is possible to carry out such cost-intensiveproduction steps such as bonding with pretested 1st and 2nd modules of aradiofrequency power semiconductor module, whereby costs and reject ratecan be considerably reduced.

In one embodiment of the invention, the housing frame may be producedfrom a plastic housing composition. The plastic material of this plastichousing composition may correspond to the plastic housing compositionthat is used for complete packaging of radiofrequency semiconductorcomponents on a flat conductor frame. In the case of the presentinvention, it is possible to produce the housing frame on the flatconductor frame independently of the production of the 2nd module andthus independently of the fixing of the radiofrequency semiconductorcomponents on a chip island. The same applies to the production of ahousing frame made of a ceramic composition. The use of ceramic ashousing frame has the advantage of improved dielectric propertiescompared with the plastic housing frame. However, the production of aceramic housing frame is associated with higher costs compared with theproduction of a plastic housing frame.

The housing frame may be one of a plurality of housing frames arrangedon a flat conductor frame. In this case, exclusively inner flatconductor ends—arranged in one plane—of each device position of the flatconductor frame are embedded in the housing frame. The flat conductorframe is of uncomplicated construction in this respect since theprovision of a chip island is completely obviated for the realization ofthe 1st module. The housing frame merely anchors the inner flatconductor ends in a plastic housing composition or in a ceramiccomposition. In this case, the inner flat conductor ends may partly bekept free of housing frame material and have refined surfaces as bondingfingers. Such refined surfaces may have nickel, gold, silver or alloysthereof in order to facilitate a reliable bonding of gold bonding wireson these uncovered flat conductor ends in the housing frame.

The downwardly and upwardly open housing frame may widen in steppedfashion from bottom to top. This stepped extension makes it possible toprovide a relatively large opening for the housing cover and to providea correspondingly reduced opening for the housing bottom in the form ofthe chip island as heat sink. The enlarged opening for the housing coverhas the advantage that a larger access opening is available for wiringthe radiofrequency semiconductor components of the 2nd module with thebonding fingers of the 1st module, said access opening facilitatingbonding from above.

The stepped formation of the housing frame from bottom to top may beconfigured in such a way that the housing frame has a lower attachment,with which the 2nd component can be brought into engagement or is inengagement. At the same time, the inner flat conductor ends can also bearranged on this lower attachment of the housing frame, the innerhousing wall being set back relative to the opening for the 2ndcomponent, so that a portion of the inner flat conductor ends remainsfree of housing frame material, so that these inner flat conductor endsthat remain free can be accessed during bonding.

An upper attachment of the upwardly open housing frame formed in steppedfashion is suitable for receiving the 3rd component as housing cover.The 3rd component can thus be brought into engagement with said upperattachment. With this 3rd component, the radiofrequency powersemiconductor module is completed and, in particular, the cavity housingis perfect. In an inexpensive version, the housing cover may comprise aplastic plate, but housing covers also based on ceramic and/or based onmetal are preferred since they permit greater power losses for theradiofrequency semiconductor components that are to be arranged in thecavity housing. Moreover, the dielectric properties of a ceramic coverare more favorable than those of a plastic cover as housing covering. Ametallic cover in turn shields the radiofrequency power semiconductormodule from electromagnetic interference sources.

In a further embodiment of the invention, the 2nd component has a metalbase, which projects from a metallic baseplate and can be brought intoengagement with the lower attachment of the housing frame. Such a metalbase may be formed in one piece with the metallic baseplate byelectrodepositing the metal base on the baseplate or machining thebaseplate on its top side in such a way that a metal base projects. Sucha metal base has the advantage that the respective radiofrequencysemiconductor component arranged on the metal base can be positionedexactly in relation to the housing frame. For this purpose, the base mayhave a height which, together with the thickness of the radiofrequencysemiconductor components, approximately has the height level like thesurfaces of the inner flat conductor ends on the lower attachment of thehousing frame, which may have a bondable coating. Such dimensioning ofthe metal base has the advantage that the bonding connections can bearranged in a single plane, which facilitates the bonding operation perse and precludes fault sources.

In a preferred refinement, the radiofrequency power semiconductor moduleaccording to the invention is a radiofrequency power amplifier (RF poweramplifier), in particular for mobile radio base stations.

The radiofrequency semiconductor components arranged on the metal basethen typically have a plurality of radiofrequency power semiconductorcomponents, in particular so-called RF-LDMOS transistors. Furthermore,an input diode and an output diode may be provided in order to protectthe radiofrequency power amplifier against overvoltage.

Moreover, a plurality of the radiofrequency semiconductor components maybe integrated circuits (ICs) in order to pass the high currents of theradiofrequency power semiconductor components to the flat conductors andconversely to take them up from the flat conductors, the radiofrequencypower semiconductor module has hundreds of bonding wires in parallelfrom the inner flat conductor ends to the electrodes of theradiofrequency semiconductor components. These hundreds of bonding wiresin practice form a flat cable with which the inner flat conductor endsare connected to the respective electrodes of the radiofrequencysemiconductor components.

The three modules of the radiofrequency power semiconductor module maybe connected to one another by means of adhesive layers or adhesivefilms. For this purpose, the adhesive may be applied to the respectiveboundary areas or joining areas of the individual modules before andafter the latter are joined together to form an electronic device.

A method for producing a radiofrequency power semiconductor module hasthe following method steps:

Firstly, a 1st module is produced. This 1st module comprises an upwardlyand downwardly open housing frame with embedded inner flat conductorends. Flat, conductors project outward from the housing frame.

A 2nd module may be produced in parallel, said 2nd module having a metalbase on a metal plate. At least one radiofrequency semiconductorcomponent is arranged on the metal base, it being possible to fit themetal base into the downwardly open housing frame.

In parallel with the production of the 1st and 2nd modules, the 3rdmodules may already be produced in the form of housing covers which canbe fitted into the upwardly open housing frame. After the production ofthe three modules, functional and quality tests of these threeindividual modules are carried out. Afterward, firstly the 1st and 2ndmodules are assembled by adhesively bonding the metal base of the 2ndmodule into the upwardly open housing frame of the 1st module. Afterassembly, the inner flat conductors of the 1st module can be connectedto electrodes of the radiofrequency semiconductor components of the 2ndmodule via the upper opening of the housing frame.

Finally, the upwardly open housing frame can be completed with the 3rdmodule to form a cavity housing. This method of modular design has theadvantage that each module can inherently be tested in respect of itsfunction and its quality before the cost-intensive step of connectingthe inner flat conductor ends to the electrodes of radiofrequencysemiconductor components is carried out. On account of the powerconsumption of the radiofrequency semiconductor components, in the caseof this connection hundreds of bonding wires are fitted in parallel onone of the inner flat conductors and placed onto one of the commonelectrodes of the radiofrequency semiconductor components.

In the case of radiofrequency power semiconductor modules, inparticular, this method has the particular advantage that only suchmodules which have no functional and quality deficiencies whatsoever areassembled to form an electronic device. This drastically reduces therejects in the production of radiofrequency power semiconductor modules.

In addition, it is possible to use a simplified flat conductor framesince this flat conductor frame only has to comprise free-standing flatconductors and does not have to have an integrally arranged chip island.

In detail, in order to produce a 1st module, a flat conductor frame witha multiplicity of device positions may be produced, flat conductors withfree-standing flat conductor ends being arranged in one plane in each ofthe device positions and a downwardly and upwardly open housing framebeing fitted in each of the device positions, the inner flat conductorends being embedded in the housing frames, while the flat conductorsproject from the housing frame. Such a continuous strip comprising aflat conductor frame with a multiplicity of device positions and housingframes arranged thereon can easily be tested with regard to its qualityand functionality, housing frames whose dimensions do not correspond tothe requirements for frictionless assembly with the other modules beingable to be marked and separated by sorting before cost-intensive methodsteps for producing the radiofrequency power semiconductor module are tobe carried out.

The free-standing flat conductor ends to be incorporated into thehousing frame may also be refined with a bondable coating on the flatconductor frame. Such bondable coatings may have nickel, gold, silver oralloys thereof. An essential feature of the quality control is, afterthe application of the housing frame, whether the bondable coating ofthe inner flat conductor ends is freely accessible or whether materialof the housing frame covers parts of said bondable coating, so that thereliable bonding is not assured. Housings with faults of this type canbe separated by sorting prior to the assembly of the 1st and 2ndmodules.

The molding of the housing frame may be effected by means ofinjection-molding of a plastic housing composition. For this purpose,the flat conductor frame is inserted into an adapted injection mold andthe free-standing inner flat conductor ends are embedded into theplastic housing composition in each of the device positions. Since theinjection-molding of plastic housing compositions can be carried outrelatively cost-effectively, it is possible to provide a flat conductorframe which has a housing frame made of plastic in each device positionafter the injection-molding.

If the housing frame is intended to comprise a ceramic material, thenfirstly a green body is molded by compression molding in each deviceposition, the free-standing inner flat conductor ends being embeddedinto the green body, formed as a housing frame. The flat conductor framewith the molded-in green body as housing frame then passes through asintering furnace, in which this green body material is sintered to forma ceramic housing frame. Although this process is more complicated thanthe injection-molding of plastic housing compositions, a ceramic housingframe affords dielectric advantages over a plastic housing frame. Inthis case of the ceramic housing frame, too, it is subsequently possibleafter sintering to carry out a quality and functional testing in thecourse of which unsuitable housing frames are marked on the flatconductor frame, so that no further modules of the cavity housing areconnected to these marked flat conductor frames.

In order to produce the 2nd module, firstly metal plates with a baseadapted to the downwardly open housing frame are produced. Afterward, atleast one radiofrequency semiconductor component is arranged on each ofthe bases and its function and connection to the base are tested. Inthis case, unsuitable 2nd modules can be separated by sorting. Thisproduction method and test method ensure that only qualitatively andfunctionally high-quality 2nd modules are connected to 1st modules ofthe cavity housing.

Before the 1st and 2nd modules are joined together, the 1st module maybe provided with an adapted adhesive film on the underside of thehousing frame. An adhesive film may also be provided for joiningtogether the 1st and 3rd modules. The use of adhesive films has theadvantage that a correspondingly structured strip of adhesive film canbe used for a plurality of housing frames on a strip-type flat conductorframe, which reduces the production costs.

After the 1st and 2nd modules are joined together, the inner flatconductor ends of the 1st module are connected to electrodes of theradiofrequency semiconductor components of the 2nd module by multipleparallel bonding of hundreds of bonding wires. In this case, the cavityhousing remains upwardly open and it is only in the last method stepthat then, given successful bonding, the 3rd module in the form of ahousing cover as termination is adhesively bonded onto the cavityhousing by means of an adhesive layer or an adhesive film. In this case,said housing cover may be produced from plastic or from metal or elseceramic. The choice of material of the housing cover essentially dependson the radiofrequency use and the power range of the radiofrequencysemiconductor components arranged on the chip island with a heat sink.While the cavity housing can advantageously be shielded againstelectromagnetic waves and interference sources with a metal cover, aceramic cover is distinguished by its better dielectric propertiescompared with a plastic cover.

To summarize, it should be emphasized that a distinction can be madebetween the following radiofrequency power housings:

-   -   1. Cavity ceramic housings, permitting a high frequency range.        These housings have a stable heat sink made of copper-tungsten        (CuW) or similar alloys onto which the radiofrequency        semiconductor components are soldered or alloyed. This        alloying-on process is carried out at temperatures of between        300 and 450° C. A ceramic lamina is mounted peripherally around        the soldered-on radiofrequency semiconductor components, flat        conductor connections made of metal being mounted on said lamina        in a manner insulated from the heat sink. Such a circuit carrier        for radiofrequency power semiconductor components is supplied in        preassembled form by a supplier. A housing concept of this type        has the disadvantage of high costs and a high outlay since        individual device handling and fabrication are required.        However, the ceramic results in high thermal stability of the        cavity housing and enables the devices to be operated in a        frequency range greater than 3 GHz.    -   2. Another variant of a radiofrequency power module housing        comprises a plastic housing injection-molded all around with an        exposed heat sink. However, such a housing with a plastic        housing injection-molded around can be used only up to        frequencies of approximately 1 GHz. Consequently, such plastic        housings injection-molded all around cannot be used for GSM and        UMTS applications. The low limiting frequency is attributable to        the capsulation of the bonding wires with plastic housing        composition and to the large dimensions between the        radiofrequency semiconductor components and the external        connections, which is realized by bonding wires of corresponding        length. Consequently, although this type of housing has        favorable production costs since composite fabrication is        possible, the limiting frequency for the radiofrequency power        devices at 1 GHz is extremely low.    -   3. It is also possible to use plastic cavity housings with an        integrated heat sink. The frequency ranges are thereby slightly        increased, but the limiting frequency range can only be        increased by a factor of 2.5 to 2.5 GHz. The        pre-injection-molded plastic cavity housings with an integrated        heat sink have the advantage of favorable production costs, but        sealing webs become necessary during the injection-molding of        the housing, so that it is not possible to optimize the        dimensions between the chip position and the inner flat        conductors. By contrast, the invention has the following        advantages:        -   1. favorable material and production costs        -   2. composite fabrication is possible        -   3. a frequency range greater than 2.5 GHz can be realized            and        -   4. the use of soldering and alloying processes, in            particular when applying the chip to the 2nd module, ensures            lower thermal resistances for high-power applications. By            way of example, a power loss during continuous operation of            240 W can thereby be realized.

The separate supply of the heat sink which, unlike hitherto, is notconnected to the flat conductor frame enables the radiofrequencysemiconductor components to be soldered or alloyed on the chip island atextremely high temperatures since the 2nd module can be producedcompletely separately from the housing frame with the flat conductorframe. Only afterward is the thermal conduction block including theradiofrequency semiconductor components inserted into the cavity housingwhilst complying with narrow tolerances of the chips with respect to theinner flat conductor ends. Consequently, the advantages of differenttechnologies can be brought together by means of the present inventionto yield a housing product that can be produced cost-effectively andsignificantly more reliably.

SUMMARY

The invention provides a power semiconductor module. In one embodiment,the invention provides a power semiconductor module with cavity housing,and method of producing the power semiconductor module.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained in more detail on the basis ofembodiments with reference to the accompanying figures.

The accompanying drawings are included to provide a furtherunderstanding of the present invention and are incorporated in andconstitute a part of this specification. The drawings illustrate theembodiments of the present invention and together with the descriptionserve to explain the principles of the invention. Other embodiments ofthe present invention and many of the intended advantages of the presentinvention will be readily appreciated as they become better understoodby reference to the following detailed description. The elements of thedrawings are not necessarily to scale relative to each other. Likereference numerals designate corresponding similar parts.

FIG. 1 illustrates a diagrammatic cross section through aradiofrequencypower semiconductor module with a cavity housing. FIGS. 2 to 7illustrates a production method for producing a radiofrequency powersemiconductor module on the basis of diagrammatic cross sections throughcomponents after individual method steps.

FIG. 2 illustrates a diagrammatic cross section through a flatconductorframe with a plurality of device positions.

FIG. 3 illustrates a diagrammatic cross section through a flatconductorframe with a fitted housing frame in a plurality of device positions.

FIG. 4 illustrates a diagrammatic cross section through a 2nd modulewith radiofrequency semiconductor components on a chip island.

FIG. 5 illustrates a diagrammatic cross section through a radiofrequencypower semiconductor module after bonding and prior to covering thecavity housing with a housing cover.

FIG. 6 illustrates a diagrammatic cross section through the 3rd moduleof the radiofrequency power semiconductor module. FIG. 7 illustrates adiagrammatic cross section through a plurality of radiofrequency powersemiconductor modules on a flat conductor frame prior to separation ofthe flat conductor frame for the production of individual electronicdevices.

DETAILED DESCRIPTION

In the following Detailed Description, reference is made to theaccompanying drawings, which form a part hereof, and in which is shownby way of illustration specific embodiments in which the invention maybe practiced. In this regard, directional terminology, such as “top,”“bottom,” “front,” “back,” “leading,” “trailing,” etc., is used withreference to the orientation of the Figure(s) being described. Becausecomponents of embodiments of the present invention can be positioned ina number of different orientations, the directional terminology is usedfor purposes of illustration and is in no way limiting. It is to beunderstood that other embodiments may be utilized and structural orlogical changes may be made without departing from the scope of thepresent invention. The following detailed description, therefore, is notto be taken in a limiting sense, and the scope of the present inventionis defined by the appended claims.

FIG. 1 illustrates a diagrammatic cross section through a radiofrequencypower semiconductor module 1 with a cavity housing 3 in one embodimentof the invention. The reference symbol 2 denotes radiofrequencysemiconductor components, of which three radiofrequency semiconductorcomponents are arranged on a chip island 4. The reference symbol 5denotes flat conductors that are anchored by their inner flat conductorends 16 in a housing frame 6 of the radiofrequency power semiconductormodule 1. The reference symbol 7 denotes a housing cover, whichhermetically seals the cavity housing 3 toward the top. The referencesymbols 8, 9 and 10 denote three modules of which the radiofrequencypower semiconductor module 1 is composed. The reference symbol 11denotes a heat sink, which essentially composes the chip island 4.

The reference 12 denotes the bottom of the cavity housing 3, which isformed by a metal base 20 of the chip island 4. The reference symbol 14denotes a housing frame, which is constructed from a plastic moldingcomposition in this embodiment of the invention. The reference symbol 15denotes a flat conductor frame, of which the flat conductors 5projecting from the housing frame 14 can be seen in this embodiment ofthe invention. The reference symbol 18 denotes bonding fingers, whichare formed by a portion of the inner flat conductor ends 16 and whichhave a refined surface in order to enable reliable bonding for thefitting of bonding wires 22.

The reference symbol 13 denotes a lower attachment of the housing frame,which is extended in a stepped fashion from bottom to top in thisembodiment of the invention, and the reference symbol 19 denotes anupper attachment, in which the 3rd component of the radiofrequency powersemiconductor module, namely the housing cover 7, can be fitted. Thereference symbol 23 denotes electrodes on the radiofrequencysemiconductor component 2. The reference symbol 24 denotes adhesivelayers and the reference symbol 25 denotes a plastic housingcomposition. The radiofrequency power semiconductor module 1 isessentially constructed from three modules 8, 9, and 10 that can beproduced separately. These three modules are configured such that theycan be adapted with respect to one another and can be inserted into oneanother.

The 1st module 8 essentially has a housing frame 6, which, in thisembodiment of the invention, is constructed from a plastic housingcomposition 25 and has been applied to a flat conductor frame 15 by aninjection-molding method. In this case, the flat conductors 5 have beenanchored in the injection-molding composition 25. In order to supportthe anchoring of the inner flat conductor ends 16 in the plastic housingframe 14, the flat conductor ends have passage openings 26. Theinjection-molding composition 25 of the housing frame 6 is provided bothabove and below the inner flat conductor ends 16, so that the inner flatconductor ends are practically embedded in the plastic housingcomposition 25 apart from a region that forms bonding fingers 18.

The housing frame 7 is open from bottom to top, the opening in thehousing frame 7 widening in stepwise fashion from bottom to top. Theinner flat conductor ends 16 are arranged on the bottommost step or thebottommost attachment 13 of the housing frame. The inner wall of thehousing frame is set back above the inner flat conductor ends 16,thereby enabling an access to the bonding fingers. An upper attachment19 is configured in such a way that it enables an opening for fitting ina housing cover.

In this embodiment, the 2nd module 9 comprises a metallic baseplate 21from which a metal base 20 can project. Baseplate 21 and metal base 20are dimensioned in such a way that they can be adapted to the lowerattachment 13.

In this embodiment of the invention, the radiofrequency semiconductorcomponents are three radiofrequency power semiconductor components whichtogether form a radiofrequency power semiconductor module. The centralradiofrequency semiconductor component is a radiofrequency powertransistor, having a source electrode S and a drain electrode D. Thegate electrode G is protected from overvoltage by an input power diode27. At the same time, a third radiofrequency semiconductor component 2in the form of a power diode 28, which forms the output diode, isaccommodated on the chip island 4. The three radiofrequencysemiconductor components or electrodes are connected to the bondingfingers 18 by means of hundreds of parallel-connected bonding wires 22or by means of a flat ribbon having a thickness of 15 to 50 μm with awidth of several millimeters.

The individual bonding wire has a diameter of between 15 and 50 μm andessentially comprises gold. The operating temperature of thisradiofrequency power semiconductor module as is shown in FIG. 1 isapproximately 200° C. The resulting power loss is effectively dissipatedto the surroundings by means of the metal base 20 and the metal plate21. The heat dissipation can be intensified by housing ribs that can beincorporated into the baseplate 21 or can be placed onto the baseplate21.

The 3rd module of this radiofrequency power semiconductor module 1 isformed by the housing cover 7. Depending on the requirements made of thehigh-power device, said housing cover may be produced from plastics,ceramic or metal. Metal covers have proved successful as a shieldingaid, while ceramic covers have improved dielectric properties comparedwith a plastic cover. Given a correspondingly high filling of theplastic cover, however, it is also possible to achieve operatingtemperatures of approximately 200° C. without the plastic cover warping.

FIGS. 2 to 7 illustrate a production method for producing aradiofrequency power semiconductor module 1 on the basis of diagrammaticcross sections through components after individual method steps.Components having functions identical to those in FIG. 1 are identifiedby the same reference symbols in the following FIGS. 2 to 7 and are notdiscussed separately.

FIG. 2 illustrates a diagrammatic cross section through a flat conductorframe 15 with a plurality of device positions 17. This flat conductorframe 15 is of simple construction and in this respect can be producedextremely cost-effectively. It essentially comprises a metal strip intowhich individual structures have been stamped which, on the one hand,constitute flat conductors 5 and, on the other hand, form free-standingflat conductor ends 16, the top side of which is in part coated with abondable coating. The flat conductor ends 16 have passage openings 26.Whereas only two device positions 17 are illustrated diagrammatically inFIG. 2, a flat conductor strip of this type may have as many devicepositions as desired.

FIG. 3 illustrates a diagrammatic cross section through a flat conductorframe 15 with a molded housing frame 6 in a plurality of devicepositions 17. Said housing frame 6 is upwardly and downwardly open. Thehousing frame 6 extends in stepped fashion from bottom to top in thisembodiment. In this case, the lower opening has a lower attachment 13,into which the 2nd module 9 can be fitted. The inner flat conductor ends16 of the flat conductors 5 are arranged on the lower attachment 13,said flat conductor ends 16 having openings 26 which are now completelyfilled by plastic housing composition, so that the flat conductors 5 areanchored in a positively locking manner in the plastic housingcomposition 25. At the same time, a portion of the inner flat conductorends 16 is kept free of housing composition, so that bonding fingers 18can be formed.

FIG. 4 illustrates a diagrammatic cross section through a 2nd module 9of the radiofrequency power semiconductor module with appliedradiofrequency semiconductor components 2 on a chip island 4 made ofmetal. Said chip island is in one piece and comprises a metallicbaseplate 21 and an emplaced metal base having a height h. Together withthe thickness d of the radiofrequency semiconductor component 2, theupper edge of the 2nd module 9 reaches the height level H of the topside of the inner flat conductor ends or the bonding fingers 18, whichis illustrated in FIG. 3. Such an adaptation of base height h and chipthickness d to the height level H of the bonding fingers facilitates thebonding of the bonding wires between the bonding fingers 18 of the 1stmodule 8 and the electrodes 23 of the radiofrequency semiconductorcomponent 2 of the 2nd module 9. For this purpose, the 2nd module 9 isintroduced into the bottom opening 29 of the housing frame 6 in arrowdirection A and connected to the lower attachment 13 of the housingframe by means of an adhesive layer.

FIG. 5 illustrates a diagrammatic cross section through a radiofrequencypower semiconductor module 1 after bonding and prior to covering thecavity housing 3 with a housing cover. The bonding wires 22 that can beseen in the cross section are laid from the bonding fingers 18 to theelectrodes 23 of the radiofrequency semiconductor component, on the onehand, and are also wired between the electrodes of the radiofrequencysemiconductor component, on the other hand. Since the bonding wires havean extremely small diameter, 500 bonding wires having a diameter of 38μm are bonded in parallel onto a common electrode of a radiofrequencysemiconductor component in this embodiment. A flat conductor comprisingthe bundle of parallel bonding wires thus arises, in principle.

The bonding, as illustrated in FIG. 5, may still be effected while theindividual electronic devices are connected to one another by means of astrip of a flat conductor frame 15, thus resulting in an efficientfabrication. Both the flat conductor frame 15 and the chip island 4 arecomponents that are structured in an uncomplicated manner and can thusbe fabricated inexpensively, thereby drastically reducing the overallprice for the radiofrequency power semiconductor module compared withdevices based on multilayer, three-dimensional flat conductor frameconstructions.

FIG. 6 illustrates a diagrammatic cross section through the 3rd module10 of the radiofrequency power semiconductor module 1. The 3rd module 10also essentially comprises a relatively simple component. Thiscomponent, as housing cover 7, is adapted in its external dimensions tothe upper attachment 19 of the housing frame 6 and can be placed ontothe housing frame 6 in arrow direction B.

FIG. 7 illustrates a diagrammatic cross section through a plurality ofradiofrequency power semiconductor modules 1 on a flat conductor frame15 prior to separation of the flat conductor frame 15 for the productionof individual electronic devices 1. For this purpose, the flat conductorframe 15 can be separated in the direction of the dash-dotted line 30,so that the flat conductor frame 15 is split into individual externalflat conductors and thus into individual fully functional radiofrequencypower semiconductor modules 1.

1-26. (canceled)
 27. A radiofrequency power semiconductor modulecomprising: a cavity housing; one or more radiofrequency semiconductorcomponents; a chip island on which the radiofrequency semiconductorcomponents are arranged, and having flat conductors anchored in anupwardly and downwardly open housing frame, and having a housing cover,the radiofrequency power semiconductor module having three prefabricatedmodules, a first module including the upwardly and downwardly openhousing frame with horizontally arranged flat conductors, a secondmodule including the chip island with the radiofrequency semiconductorcomponents as a heat sink and forming the bottom of the cavity housing,and a third module having the housing cover.
 28. The radiofrequencypower semiconductor module of claim 27, wherein the first moduleincludes a plastic housing frame.
 29. The radiofrequency powersemiconductor module of claim 27, wherein the first module includes aceramic housing frame.
 30. The radiofrequency power semiconductor moduleof claim 27, wherein the housing frame is one of a plurality of housingframes arranged on a flat conductor frame, exclusively inner flatconductor ends being arranged in one plane and being embedded in thehousing frame of each device position of the flat conductor frame. 31.The radiofrequency power semiconductor module of claim 30, wherein theinner flat conductor ends are partly free of housing frame material andhave refined surfaces as bonding fingers.
 32. The radiofrequency powersemiconductor module of claim 27, wherein the housing frame widens in astepped fashion from bottom to top.
 33. The radiofrequency powersemiconductor module of claim 27, wherein the housing frame has a lowerattachment, with which the second module can be brought into engagement.34. The radiofrequency power semiconductor module of claim 33, whereinthe inner flat conductor ends are arranged on the first attachment ofthe housing frame.
 35. The radiofrequency power semiconductor moduleclaim 27, wherein the housing frame has an upper attachment, with whichthe third module can be brought into engagement.
 36. The radiofrequencypower semiconductor module of claim 27, wherein the second component hasa metal base, which projects from a metallic baseplate and can bebrought into engagement with the lower attachment of the housing frame.37. The radiofrequency power semiconductor module of claim 27, whereinthe base has a height, which, together with the thickness of theradiofrequency semiconductor components, approximately has the heightlevel of the surfaces of the inner flat conductor ends on the lowerattachment of the housing frame.
 38. The radiofrequency powersemiconductor module of claim 27, wherein the radiofrequencysemiconductor components include at least one radiofrequency powersemiconductor component.
 39. The radiofrequency power semiconductormodule of claim 27, wherein the radiofrequency semiconductor componentsinclude at least one radiofrequency IC.
 40. A radiofrequency powersemiconductor module comprising: a cavity housing; one or moreradiofrequency semiconductor components; a chip island on which theradiofrequency semiconductor components are arranged, and having flatconductors anchored in an upwardly and downwardly open housing frame,and having a housing cover, the radiofrequency power semiconductormodule having three prefabricated modules, a first module including theupwardly and downwardly open housing frame with horizontally arrangedflat conductors, a second module including the chip island with theradiofrequency semiconductor components as a heat sink and forming thebottom of the cavity housing, and a third module having the housingcover; and wherein hundreds of bonding wires are bonded, in parallel,from the inner flat conductor ends to the electrodes of theradiofrequency semiconductor components.
 41. The radiofrequency powersemiconductor module of claim 40, wherein at least one flat ribbonhaving a thickness of 15 to 50 μm in a width of a plurality ofmillimeters is bonded from the inner flat conductors to the electrodesof the radiofrequency semiconductor components.
 42. The radiofrequencypower semiconductor module of claim 40, wherein the three modules of theradiofrequency power semiconductor module are connected to one anotherby means of adhesive layers or adhesive films.
 43. A method forproducing a radiofrequency power semiconductor module, comprising:producing a first module having a downwardly and upwardly open housingframe with embedded inner flat conductor ends, flat conductorsprojecting from the housing frame; producing a second module having ametal base on a metal plate, at least one radiofrequency semiconductorcomponent being arranged on the metal base and the metal base beingadaptable to the downwardly open housing frame; producing a 3rd modulehaving a housing cover that can be fitted into the upwardly open housingframe; carrying out of functional and quality tests of the threeindividual modules; assembling the first and second modules byadhesively bonding the metal base of the second module onto thedownwardly open housing frame of the first module after a successfulfunctional and quality test; connecting the inner flat conductor ends ofthe first module to electrodes of the radiofrequency semiconductorcomponents of the second module; covering of the upwardly open housingframe with the third module.
 44. The method as claimed in claim 43,wherein producing a first module comprises producing a flat conductorframe with a multiplicity of device positions, flat conductors withfree-standing flat conductor ends being arranged in one plane in each ofthe device positions and a downwardly and upwardly open housing framebeing fitted in each of the device positions, the inner flat conductorends being embedded in the housing frames, while the flat conductorsproject from the housing frame.
 45. The method as claimed in claim 43,comprising refining the free-standing flat conductor ends with abondable coating.
 46. The method of claim 43, comprising molding thehousing frame by means of injection-molding of a plastic housingcomposition into an injection mold adapted to the flat conductor framewith the free-standing inner flat conductor ends being embedded into theplastic housing composition in each device position.
 47. The method ofclaim 43, molding the housing frame by means of compression molding of aceramic green body with the free-standing inner flat conductor endsbeing embedded into the green body in each device position, the greenbody subsequently being sintered to form a ceramic housing frame. 48.The method of claim 43, comprising: checking and testing each housingframe in each of the device positions; and marking unsuitable housingframes on the flat conductor frame.
 49. The method of claim 43, whereinproducing the second module comprises, firstly producing metal plateswith bases adapted to the downwardly open housing frame, and at leastone radiofrequency semiconductor component is arranged on each of thebases and its function and connection to the base are tested; andseparating unsuitable second modules by sorting.
 50. The method of claim43, wherein the connection of the inner flat conductor ends of the firstmodule to electrodes of the radiofrequency semiconductor components ofthe second module is effected by multiple parallel bonding of hundredsof bonding wires between one of the inner flat conductor ends and one ofthe electrodes of the radiofrequency semiconductor component.
 51. Themethod of claim 43, comprising applying a nickel, gold, silver or analloy thereof on the inner flat conductor ends as a bondable coating.52. The method of claim 43, comprising laminating the first module withadhesive films in preparation for the connection to the second and/orthird module.
 53. A radiofrequency power semiconductor modulecomprising: a cavity housing; one or more radiofrequency semiconductorcomponents; a chip island on which the radiofrequency semiconductorcomponents are arranged, and having flat conductors anchored in anupwardly and downwardly open housing frame, and having a housing cover,the radiofrequency power semiconductor module having three prefabricatedmodules, first module means including the upwardly and downwardly openhousing frame with horizontally arranged flat conductors, second modulemeans including the chip island with the radiofrequency semiconductorcomponents as a heat sink and forming the bottom of the cavity housing,and third module means having the housing cover.